1. Technical Field
The present invention relates generally to an apparatus and method for producing an anti-freeze water solution and particularly concerns an apparatus and method for replenishing fluid within an automobile windshield washer reservoir.
2. Discussion
Currently available automobile windshield washer systems employ the use of a manually replenished anti-freeze solution reservoir from which a windshield washer anti-freeze solution is drawn for delivery to a windshield surface. Commonly used washer solutions include methanol-water mixtures or ammonia-methanol-water mixtures. These solutions are mixed at preselected ratios appropriate for achieving sufficient freezing point depression to avoid freezing of the washer solution in the climate of their use.
Disadvantages associated with this type of system include the safety concern of poor driver visibility associated with depleting the washer solution supply in transit when additional fluid is required to clean the windshield surface. In addition, there is inconvenience associated with the required frequent refilling of the windshield washer reservoir, especially during winter months when the fluid is used most often. Because of the demand for large quantities of windshield washer solution during these periods, current systems must maintain a reservoir of sufficient size to prevent constant refilling of the system from becoming necessary. A large windshield washer reservoir, however, occupies a substantial amount of space within an automobile engine compartment and when filled to or near capacity, adds weight to the vehicle. Thus, the current designs for automobile windshield washer systems are detrimental toward efforts directed to achieving greater space efficiency for reducing engine compartment size and reducing vehicle weight.
Because the operation of an automobile windshield washer system during cold winter weather conditions requires a windshield washer fluid that remains in liquid form at low temperatures, the use of pure water as a washer fluid is impractical or impossible, as winter temperatures commonly fall below the freezing point of the water. It is therefore essential that a freezing point depressant additive be introduced to water used for cleaning the windshield. Available freezing point depressants include alcohols such as methyl alcohol, propylene glycol, isopropyl alcohol, ethyl alcohol, and ethylene glycol. In typical windshield washer systems, an alcohol additive such as the above is combined with water to form an anti-freeze washer solution.
Because adequate freezing point depression for many applications is obtained for methanol-water windshield washer solutions having 60% to 70% water, both the size and the required replenishment frequency of the anti-freeze washer solution reservoir could be reduced if a replenishment of the water component of the solution could take place aboard an automobile in operation and such water combined with liquid from a concentrated anti-freeze liquid reservoir to form a mixed windshield washer solution of selected concentration.
Several methods have been disclosed in the prior art for obtaining a water supply for various uses aboard an automobile. U.S. Pat. Nos. 3,199,307 to Willis; 3,210,956 to Maier et al.; 3,498,076 to Michael; and 3,882,692 to Watanabe et al. all disclose the collection of water from automobile air conditioning units. Use of these methods as a means for obtaining water to mix with a pure anti-freeze liquid would require that the automobile air conditioning unit be in operation at those times when replenishing of the windshield washer fluid reservoir becomes necessary. As a matter of common practice, however, automobile air conditioning units are not in constant use during the winter months of highest demand on a windshield washer system, as they tend to be used only for temporary initial defogging or defrosting purposes. Therefore, some alternate means must be employed for collecting water aboard an operating automobile for addition to a windshield washer system.
U.S Pat. No. 3,846,866 to Bryant discloses an apparatus for collecting road surface water by utilizing the flinging action of a rotating tire. Use of this type of system for the present application would not be practical, however, for several reasons. Such a system is dependent upon the presence of adequate amounts of water on the road surface below the automobile to be collected through the flinging action of one or more tires. Further, such road surface water is likely to include substantial amounts of dirt and particulate matter, including small stones, which must be removed by a filtering means to produce a windshield washer solution that will not clog water or washer solution supply lines, will not damage pumps used to transport water and washer solution throughout the washer system and will not scratch an automobile windshield by the action of windshield wipers.
Accordingly, the need exists for an improved method and apparatus for automatic replenishment of a windshield washer system during automobile operation. Most importantly, the need exists for an improved means for automatically replenishing the water component of an automobile windshield washer system during automobile operation.